Device for producing soap lather and use thereof

ABSTRACT

Soap lather dispensers are known which process soap solution and air via a flexible arrangement in a foaming unit to produce lather. These devices are either costly to manufacture or produce lather of unreliable and/or poor quality. A uniform lather quality can be ensured independently of the actuation path (P) by a metering pump (1) which operates synchronously with the air pump (12) and has no dead spaces. With special blower units, in particular by the incorporation of the foaming unit (18) in an air chamber (17), the lather quality is further improved. The device is suitable in particular for frequent use in public washrooms.

The present invention refers to an appliance for the formation of soapfoam, with a soap solution metering pump actuated by a single lever,containing a reciprocating piston in its cylindrical space, and a devicefor compressing and introducing air, coaxial to the metering pump andcapable of reciprocating motion, and moved synchronously with thelatter, and in which openings and/or ducts which are capable of beingclosed lead into a foaming unit where fine-bubbled foam portions areformed.

BACKGROUND OF THE INVENTION

A device corresponding to the preamble for dispensing cleaning ordisinfection agents or the like is known from CH-A5-676 227. This designis based on production engineering adaptations to the designs in EP-A1-0019 582 and EP-A1-0 079 853.

The foaming unit used here is also already known (CH-A5-676 456) and ismost commonly used in the closures and dispensers fitted to bottles,usually plastic. Pressing the bottle walls causes liquid and air to bepressed into the "foamer" mounted on the bottle, where it is swirled,foamed, forced through a microfilter and dispensed directly at thenozzle as foam. In all the design forms, tolerances necessary forproduction engineering reasons are compensated by relative movementbetween the parts.

The known appliances are of relatively complicated construction (EP-A1-0019 582 and EPA1-0 079 853) or leave something to be desired in theirfoam quality (CH-A5-676 227). The sizes of the individual foam portionsdiffer with slow movements and quick movements of the lever; the valvesand arrangements used tend to dribble. In addition, the air buffers inthe metering pump, which are intended to ensure the ejection of thesoap, have a negative effect on the constancy of the metered quantity.

BRIEF SUMMARY OF THE INVENTION

The task of the invention is therefore to create a device which does notexhibit the disadvantages of the state of the art, has high operationalreliability and, even after prolonged interruptions, delivers perfect,fine-pored foam. At the same time the construction should beeconomically designed and in particular be suitable for mass production.

The task is solved by designing the cylindrical space as flat at its endface, arranging a ball inlet valve and spring-loaded ball outlet valveopposite each other at the end face of the cylindrical space, designingthe piston head as flat at its end face, and arranging the lever so thatit forces the piston to make positive contact with the end face of thecylindrical space when in its end position.

The design of the cylindrical space in accordance with the inventionallows precise and synchronous metering of liquid soap and of air, sothat uniform foam formation results regardless of lever travel.Furthermore, the fact that the end face of the piston makes contact withthe end face of the cylindrical space gives a defined stroke and thusdefined delivery quantities, without any residual volumes occurring.This solution is also favourable and inexpensive from a productionengineering viewpoint; other positive contact designs of the piston andthe cylindrical space are equally feasible, but less favourable foradjusting to each other.

The optimum arrangement of the valves is equally important forrepeatable metering of the soap solution.

Incorporation of a chamfered piston face and cylindrical space isfavourable from a production engineering viewpoint and allows thecontact surface between the piston and the cylindrical space to beprecisely defined without subjecting either of the two parts to wear.

The selection of the ball for the inlet valve with a lower density thanthat of the soap solution results in a valve ball which floats in thesoap solution and is therefore always fully ready for use.

Balls made of elastomer have proved particularly successful, as thisgives optimum sealing tightness with minimal spring pressure.

Inclusion of an expansion/conditioning chamber downstream of a foamingunit which in itself is already known gives improved foam quality andallows the foaming unit to be protected against drying out.

The siphon-like expansion/conditioning chamber is especially favourable;it serves on the one hand to compress and homogenise the foam, and onthe other hand its vertical part can be easily cleaned.

The incorporation of a facility for coaxially blowing through theconditioning part, increases the operational readiness of the appliance,particularly after prolonged periods of non-use.

The utilisation of the compressed air produced in the air pump forblowing through, or for pressure generation, is particularly favourable.

Inserting an intermediate orifice forces the soap foam to contract, andcontributes to its homogenisation after the subsequent repeatedexpansion. In addition, once the soap foam has been blown out, theorifice acts against the downstream expansion part as a defined boundaryof minimum area and thereby reduces the ingress of air into theconditioning part and the foaming unit.

The addition of an anti-fluctuation chamber ensures an even coaxial flowtowards the foaming unit, which in itself is already known.

The air buffer can be realised in a simple form by a outer ring groovein the foaming unit, and improves the flow conditions in the inletregion of the foaming unit.

Due to its very low consumption of soap solution, the appliance inaccordance with the invention is ideally suited for use in publicwashrooms, particularly in toilets. The appliance is largelymaintenance-free; the soap solution bottle can be replaced every fewdays or every few weeks, depending on frequency.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Practical design examples of the object of the invention are describedbelow with the drawings. The same functional parts are designated by thesame item numbers in all the drawings.

For reasons of clarity, the usual hatching has been omitted in severalof the drawings; they are therefore referred to as quasi-sectionaldrawings.

These are:

FIG. 1 a perspective view of a lever-actuated foam dispenser, as aquasi-section

FIG. 2 an enlarged view of a foaming unit as in FIG. 1, with thecomponents which enclose it immediately, shown as a normal sectionalview

FIG. 3 a further development of foam dispenser, utilising the entirevolume of the housing, as a quasi-section,

FIG. 4 a variant of a foam dispenser, intended for actuation by foot,and

FIG. 5 a further variant of foam dispenser, actuated by a push button,

FIG. 6 another foam dispenser, also actuated by a push button, anddesigned as a free-standing table-top model.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a foam dispenser, which is compatible with the previousmodel in accordance with EP-A1-0 019 582 and EP-A1-0 079 853 andmillions of which have been manufactured. The item 1 is a metering pumpwith a cylindrical space 2 for soap solution. This cylindrical space 2has a flat surface at the end. An inlet valve 4 with a floating ball 4ais arranged above the flat surface, and an outlet valve 5 with a ball 5aopposite it underneath. Corresponding inlet and outlet passagesdesignated 21 and 22 respectively lead into a chamfer 20 in thecylindrical space 2. A piston head 24, with a chamfer 25 at the sameangle and a flat end face 23, has a seal 26, in the form of acommercially-available O-ring, and is operated by a flexible piston rod27 with a hollow space 28. At its end, the piston rod 27 has a flatsliding pressure surface 29, against which the cam 30 of a yoke 31 witha bracing strut 32 and a ring-shaped actuator lever 33, used to operatethe dispenser, presses.

An air pump 12 is arranged concentric to the metering pump, which via acompression spring 13 supported in its housing presses a flexible piston14 with double lips and an O-ring seal 15 into the rest position shownin the drawing.

A supporting bracket/adapter 36 acts as a housing cover for the air pump12. This also accommodates a rear bearing 34 (shown in the drawing) anda front bearing (not shown in the drawing) for the yoke 31, and by meansof a mounting rail 37 on the back, provides a method of mounting wherebythe appliance can be slid on to a well-known appliance housing, notshown in the drawing. The ball 5a of the outlet valve 5 is pressed intoa corresponding valve seat by a valve spring 9, while the second end ofthe valve spring 9 rests in a bore in a foaming unit 18, shown in planview. Below the foaming unit 18, and connected to it by a mixing nozzle,is the expansion part 19a of an expansion/conditioning chamber, with aninitial cross section q1. The expansion part 19a leads into aconditioning part 19b, with an orifice of rectangular shape 19cinterposed between the two parts 19a and 19b. The cylindrical crosssection q2 in the part 19b is larger than the cross section q1, which isalso cylindrical. An air outlet 16 is provided in the end-face area ofthe cylindrical space 11 of the air pump 12, which is connected to theinterior space of an anti-fluctuation chamber 17 in which the foamingunit 18 is arranged concentrically.

The inlet valve 4 is connected by a hole 4' to the interior space of ahousing 38, which acts as a temporary soap reservoir. This temporaryreservoir is supplied with liquid soap by a well-known bottle, not shownin the drawing, screwed into a connection 39 which forms part of a cover40 of the housing 38.

The housing 38 accommodates an air passage 41 connected to the rear ofthe air pump 12 and leading to a ring duct 42 incorporated in the cover40, which in turn is connected to a vertical air supply 43, a horizontalair supply 44 and a blow-out duct 45,45'. A blow-out valve 6 with acorresponding valve ball is located at the end of the blow-out duct 45'.A cylindrical inlet flow adjuster is provided below the valve 6, andarranged concentric with the top. end of the conditioning part 19b.

The method of operation of the appliance as shown in FIG. 1 is asfollows:

When the actuator lever 33 is pulled by hand in the direction of thearrow P, it acts on the piston rod 27, on which the flexible piston 14and the piston head 24 are arranged. The effect of this--when thecylindrical space 2 is filled--is to convey soap solution and air at thesame time; the air inlet valve 7, with valve cover 8, shuts at the startof the piston rod stroke. The soap pushes the floating and resilientball 4a upwards and the ball 5a downwards, i.e. soap solution andcompressed air are delivered to the foaming unit 18 and there convertedto foam.

The soap foam thus formed expands first in the mixing nozzle 53 of thefoaming unit 18 and then in the horizontal region of the expansion part19a; the foam which follows then pushes the foam formed first throughthe vertical cylindrical-shaped region of the expansion part 19a; it isthen compressed in the orifice 19c, re-expands in the larger crosssection q2 and is conditioned in the part 19b before leaving through theoutlet nozzle 10.

The conditioned foam ejected through the outlet nozzle 10 is of a highhomogeneity and fineness, and is stable in its volume.

When the lever 33 is released, the spring 13 presses the piston 14backwards again, so that air is compressed by a double-acting piston andflows through the ducts 41 to 45' into the air inlet part 10 and ejectsall the foam present in the expansion part 19a.

The appliance is then ready for use again, as the floating valve ball 4ais lifted off its valve seat at the start of the return stroke by thestatic soap pressure in the temporary reservoir, so that the cylindricalspace 2, supported by the partial vacuum, fills with soap completely.

The valves used are arranged so that their rest position corresponds totheir shut position. This ensures that they fulfil their function evenwith very small flows (virtually static). In addition, the ball guide isdesigned for a small gap width of approximately 0.5 mm; the ball guideconsists in a known manner of four boundary surfaces, so that anysticking is rectified by the hydraulic forces already operating on theball.

Commercially-available balls made of elastomer, particularly siliconerubber, have proved to be highly suitable.

The pressure range, measured at the outlet of the metering pump, extendsto a maximum of 1.5 bar; the air pressure, measured at the outlet of theair cylinder, indicates a maximum pressure of 0.2 bar.

The typical duration of actuation of the foam dispenser is in the orderof one second. Shorter or longer actuations do not have any adverseeffect on the foam quality.

The optimum metering volume has proved to be 0.4 ml of soap solution perstroke, with an approximately 30-fold volume increase into foam. Theresulting foam volume of 12.5 cm³ gives the illusion of a "piece" ofsoap due to its high consistency.

As can be seen in FIG. 2, the foaming unit 18, which is a known item(CH-A5-676 456) is surrounded by an inner flange 61, which in turn ispartially surrounded by an outer flange 62 and mounted in a detachablemanner underneath the valve 5 and concentric with it.

It can be easily seen from FIG. 2 that the metered quantity of soapsolution flows into the foaming unit 18 through a central mixing duct 54in an inlet flow adjuster 56. At the same time, a volume of air,compressed synchronously with this, is introduced through a so-calledanti-fluctuation chamber 60 into the mixing duct 54, where it encountersthe conical deflector 50; the foam formation starts, due to a continuousswirling of soap solution and air, without any interruptions. The coarsefoam thus formed then pushes through a commercially-availablemicrofilter (fleece), which is not shown in the drawing, and six coaxialholes in a mixing element 51 into a mixing chamber 52, where it is madefiner. The foam enters the expansion part 19a through a mixing nozzle53, the volume of which is smaller than that of the expansion part 19a,and is pushed by the foam following behind it so that it changesdirection through the rectangular orifice 19c into the expansion part19b and, as described above, into the outlet nozzle 10.

At its top end the inlet flow adjuster 56 has a deep, circumferentialgroove which acts as an internal air buffer 55 and, like theanti-fluctuation chamber 60, ensures a smooth introduction of the airinto the mixing duct 54. This kind of inflow into the foaming unit 18 isvery largely responsible for the continuous swirling described above andin this way initiates the high-quality foam formation.

The inlet flow adjuster 56 is retained by a support flange 57, held inplace by the latter's circumferential locking part 28 and positionedsymmetrical to the axis by a centring bush 59.

All the parts in FIG. 2 are dimensioned to fit inside one another andare fixed by screws and seals, not shown here, to the metering pump inFIG. 1 by corresponding flanges. Similarly, the end of the blow-out duct45' is fitted to the remaining part of the duct in FIG. 1.

While the soap foam dispenser in FIG. 1 and FIG. 2 is designed to fit anexisting model, or to fit in its housing, the designs in FIGS. 3 to 6represent individual solutions of different designs to the subject ofthe invention.

FIG. 3 shows a foam dispenser which although capable of beingaccommodated in a housing of the known type, is fitted with a soapbottle 70 which has a greater volume than that used in the arrangementshown in FIG. 1.

The appliance housing 71 is intended for mounting on a wall W, usuallyabove a washbasin.

The components known from FIGS. 1 and 2 are also present here, but themetering pump 1 has a fixed piston head 24, with two outlet passages 22'running through it. A piston rod 27' containing the cylindrical space 2,and incorporating the flexible piston 14 with is lip seal 15', isarranged so that it can be moved axially. The outlet valve 5, aspreviously described, is arranged in an axial direction in the foamingunit 18 at the end of the outlet passage 22. Its ball is pressed againsta valve seat by a spring 9 over the bore 22'. The foaming unit 18 againhas the described outflow aid in the form of an anti-fluctuation chamber17. The mixing nozzle 53, which is horizontal here, dischargestransversely through the expansion part 19a into theexpansion/conditioning chamber, which is again of a siphon-type design.

All the other parts correspond to the arrangement in FIG. 1; theexception is that the blow-out duct 45' is connected to the air outlet16 of the air pump 11, which is preloaded by the spring 13, by adifferently-routed variant of a ring duct 42'.

The appliance shown in FIG. 4 is also intended for mounting on a wall W;the actuation force P acts here vertically on the lever 31 or 31' and isapplied by a Bowden cable 72. This model is primarily intended foractuation by foot by a means not shown here (pedal, push button, etc.).

In this version the cam 30 acts on the vertical air pump 12. The otherparts correspond to appliances already described, the exception beingthat the inlet valve 7 is here arranged asymmetrically to thecylindrical space 11, and the horizontal air supply is marked as 44.

This appliance has the advantage of hygienic actuation and, by virtue ofits compact design, can accommodate a larger soap bottle 70 and a largertemporary soap reservoir 38'.

The appliance shown in FIG. 5, which is also intended for wall mounting,is of similar construction to the previous models. Actuation here is bythe actuation button, which protrudes from the appliance housing 71 withits piston rod 27'.

The air supply for the blow-out process here is also asymmetric, via airsupply ducts shown by dotted lines 43' and a ring duct 42'. In addition,a relatively solid central bearing 74 is provided which absorbs themoments resulting from any non-axial action of the actuation force P onthe button 33 or the piston rod 27', and transmits them to the housing71.

The appliance shown in FIG. 6 can be constructed as a table-top model.The components discussed above can again be seen here, as can thereinforced central bearing 74 and a suction tube 73 extending into thesoap bottle 70' underneath. The short air supply 44', which also flowsthrough a inlet flow adjuster 46 coaxially to the conditioning part 19b,is advantageous here, so that a portion of foam is dispensed to a handheld under the outlet nozzle 10.

The housing 71' can naturally be made free-standing, and glued to thetable T if required.

Contrary to the appliances described above, the last two are fortwo-hand operation.

It has been shown that the object of the invention, in the combinationof a metering pump without dead spaces and working in a repeatablemanner, together with precision-closing valves, and with a pulse-free,encapsulated foaming unit with a coaxial inflow, produces an outstandingfoam quality with very low soap consumption. Long-term tests have shownthat at least 1000 hand washings can be done with 400 ml of soapsolution.

The appliance is therefore very environmentally-friendly in operationand clean (drip-free), ergonomically favourable and, by virtue of itsoperational reliability, extremely well suited for installation inpublic washrooms.

We claim:
 1. Appliance for forming soap foam, with a metering pump (2,24, 25, 27) for soap solution, actuated by a single lever (31, 33), witha piston capable of reciprocating motion (24, 25, 27) within acylindrical space, and a device for compressing and introducing air(12), coaxial to the metering pump (2, 24, 25, 27) capable of reciprocalmotion and moved synchronously with the latter, in which openings and/orducts (22, 16) which can be closed lead into a foaming unit (18) wherefine-bubbled foam portions are formed, characterised by the fact thatthe end face of the cylindrical space (2) is flat in shape, that aninlet ball valve (4) and a spring-loaded outlet ball valve (5) arearranged opposite each other at the flat end face of the cylindricalspace, and that the end face of the piston head (24) is flat, and thatthe lever (31, 33) presses the piston (24, 25, 26, 27) so that it makespositive contact against the end of the cylindrical space (2) when inits end position.
 2. Appliance as in claim 1, characterised by the factthat end faces of the piston (24, 25, 26, 27) and the cylindrical space(2) are chamfered round their circumference (25, 20) to match eachother.
 3. Appliance as in claim 1, characterised by the fact that theball (4a) of the inlet valve (4) has a lower density than the soapsolution to be metered.
 4. Appliance as in claim 3, characterised by thefact that the ball (4a) of the inlet valve (4) is made of elastomer. 5.Appliance as in claim 1, characterised by the fact that anexpansion/conditioning chamber (19), cylindrical in shape, is connectedto the foaming unit (18).
 6. Appliance as in claim 5, characterized bythe fact that the expansion/conditioning chamber (19) includes avertically-arranged conditioning part (19b) having a first cross-sectionand an expansion part (19a) having a second cross-section, the firstcross-section being larger than the second cross-section.
 7. Applianceas in claim 6, characterised by the fact that an air blast at a pressure(P) is blown coaxially through the vertical conditioning part (19b) froma blow-out duct (45, 45').
 8. Appliance as in claim 7, characterised bythe fact that the blow-out duct (45, 45') is connected to an outlet froman air pump (12).
 9. Appliance as in claim 7, characterised by the factthat an orifice (19c) is interposed between the expansion part (19a) andthe conditioning part (19b).
 10. Appliance as in claim 1, characterisedby the fact that an anti-fluctuation chamber (60) is incorporatedupstream of the foaming unit (18).
 11. Appliance as in claim 10,characterised by the fact that an internal air buffer (55) is includedin the foaming unit (18) in addition to the anti-fluctuation chamber(60).